Enhancing the Stability of LiNi0.5Mn1.5O4 by Coating with LiNbO3 Solid-State Electrolyte: Novel Chemically Activated Coating Process versus Sol-Gel Method

Abstract

LiNbO3-coated LiNi0.5Mn1.5O4 spinel was fabricated by two methods: using hydrogen-peroxide as activating agent and sol-gel method. The structure of the obtained cathode materials was investigated using a scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and the electrochemical properties of the prepared cathodes were probed by charge-discharge studies. The morphology of the coating material on the surface and the degree of coverage of the coated particles were investigated by SEM, which showed that the surface of LiNi0.5Mn1.5O4 particles is uniformly encapsulated by lithium innovate coating. The influence of the LiNbO3 coating layer on the spinel’s properties was explored, including its effect on the crystal structure and electrochemical performance. XRD studies of the obtained coated active materials revealed very small expansion or contraction of the unit cell. From the capacity retention tests a significant improvement of the electrochemical properties resulted when a novel chemically activated coating process was used. Poorer results, however, were obtained using the sol-gel method. The results also revealed that the coated materials by the new method exhibit enhanced reversibility and stability compared to the pristine and reference ones. It was shown that the morphology of the coating material and possible improvement of communication between the substrates play an important role.

Styrene-Based Poly(ethylene oxide) Side-Chain Block Copolymers as Solid Polymer Electrolytes for High-Voltage Lithium-Metal Batteries

“…For the preparation of the cathodes, 0.9 g of NMC622 (BASF Toda, 90 wt %) or 0.9 g of Li­[Ni 0.5 Mn 1.5 O 4 ] (LNMO) (kindly provided by Binder, 90 wt %), 0.07 g of conductive carbon (Super P, Imerys, 7 wt %), and 0.03 g of binder (poly­(vinylidene fluoride) (PVdF) 1100, Kureha, 3 wt %) were weighed in a sample container and 2 mL of N -methyl-2-pyrrolidone (NMP) was added. The container was transferred to a Thinky centrifugal mixer and stirred twice for 5 min at 1700 rounds per minute.…”

Effects of Coating on the Electrochemical Performance of a Nickel-Rich Cathode Active Material

“…The initial step of the wet process method involves the dissolution of LNO precursors in a solvent. Mereacre et al [22] have shown that along with this solvent the addition of hydrogen peroxide might improve the LNO coating through surface activation [22]. Li et al [20] investigated the effect of LNO coating on nickel-rich NMC using a wet mixing method followed by heat treatment.…”

Strong-Acid-Catalyzed Formation of Crystalline LiNbO3 at Low Ambient Temperatures

“…At normal conditions, the lowest temperature reported so far for obtaining crystalline LiNbO 3 is 400 °C . Recently, we have also reported the synthesis of LiNbO 3 from ethoxides and their use for the coating of LiNi 0.5 Mn 1.5 O 4 oxides . In this work, we used several different procedures for the synthesis of LiNbO 3 .…”

“…In this work, we used several different procedures for the synthesis of LiNbO 3 . The first procedure was similar to an earlier-reported one and involved the reaction of lithium ethoxide and niobium ethoxide in a 1.15:1.00 mole ratio in absolute ethanol and H 2 O 2 (30%) at room temperature. As a result, a clear yellowish solution was produced.…”

“…XRD patterns of the product LN-1 synthesized by the reported method and heated at various temperatures: 80 °C (black), 400 °C (red), 450 °C (blue), and 500 °C (green). The diffraction peaks corresponding to different planes are labeled.…”